A day before the South Carolina primary, it's almost anyone's game in the Palmetto state.

Once the clear front-runner, Mitt Romney's lead both in the state and nationally appeared to be evaporating quickly. Romney is leading Newt Gingrich by only 10 percentage points, sharply down from the 23 percentage-point margin at the beginning of the week, according to a new Gallup poll released today.

"Romney is a considerably weaker front-runner among Republican registered voters nationally than he was at the beginning of the week," Gallup said.

The former Massachusetts governor doesn't place much better in state polls.

A survey by Politico found Romney leading Gingrich by only 7 points. Romney holds a 10 percentage-point lead over the former House speaker, which is about half of what it was earlier this month, a poll by NBC News-Marist showed.

Both polls were conducted before Thursday night's debate, in which Gingrich once again shone in the narrow field. Gingrich received two standing ovations, becoming the only candidate to get this honor in all 13 debates of the primary season.

Gingrich is riding high from his performance at the CNN debate. And it wasn't just his lashing out at moderator John King for opening up the debate with questions about his second wife's comments to ABC News that he wanted an "open marriage." Gingrich was also helped by a flat performance by his chief rival, Mitt Romney, who struggled to answer questions about his tax record, even drawing boos from the crowd at one point.

"This was a gift for Newt Gingrich. This only is going to help the momentum," Republican strategist and ABC News contributor Matthew Dowd said, referring to ex-wife Marianne Gingrich's claims. "He could easily -- because of that answer last night -- tomorrow win South Carolina."

Gingrich also received an endorsement from conservative movie star Chuck Norris, who said in an editorial today that "Newt's experience, leadership, knowledge, wisdom, faith and even humility to learn from his failures (personal and public) can return America to her glory days."

Gingrich campaigned heavily in the state today but canceled an appearance this morning at the Southern Republican Leaders Conference because of weak attendance. The attendance at the entire conference appeared to be sparse but Rep. Ron Paul and Rick Santorum spoke there anyway. Former candidate Herman Cain was the only one who drew a larger-than-usual crowd.

Romney continues to take hits on the tax front. He has tried, unsuccessfully, to downplay his wealth and has said he would release his tax records in April, despite calls for him to release the information now. Gingrich released his 2010 tax records Thursday.

Romney, on the flip side, has called on the former speaker to release documents from the ethics investigation during his time as House speaker. While the House ethics committee report has already been made public, Gingrich said last year that he had turned "one million pages of material" over during the investigation, materials that Romney says should now be released.

"I think over 80 percent of Republican congressmen voted to reprimand the speaker of the House; first time in history," he said today. "[House Minority Leader] Nancy Pelosi has the full record of that ethics investigation."

Pelosi has said she is not sitting on a trove of opposition research on Gingrich.

Romney took a more cautious approach today, saying he is "pretty confident, cautiously optimistic" about Saturday's primary but continued to skirt questions about his tax records.

"When I look at the crowd this morning, my enthusiasm meter went up, my confidence goes up," he said. "But we'll see what the numbers are in the final tally."

But Gingrich isn't without his own challenges. Santorum, another conservative favorite, has also built considerable momentum in the past week in South Carolina and is likely to take away votes from Gingrich, thereby helping Romney. Santorum's victory in the Iowa caucuses, announced Thursday, helped jolt new momentum into his campaign, which could hurt Gingrich Saturday.

The former Pennsylvania senator also delivered a strong performance at Thursday night's debate, challenging both Gingrich and Romney and vying to establish himself as the conservative alternative to Romney.

Then there's also Rep. Ron Paul. The congressman from Texas has yet to build as strong of a support group in South Carolina as he did in the first two voting states, but remains a strong force on the campaign trail.